1. Field of the Invention
The invention relates to an arrangement for making a photograph, photographic slide or cine-film recording of a television picture, the arrangement comprising a television picture signal source for producing a picture signal with line and picture field or picture frame periods, a television display arrangement having a picture display screen and receiving the picture signal to display a raster line television picture, a photographic, slide or cine-film camera directed towards the picture display screen for photographing the television picture, and a line structure correction circuit for reducing the visibility of the raster line structure of the television picture.
2. Description of the Related Art
Such an arrangement is proposed in U.S. Pat. No. 4,096,530. Without the use of the line structure correction circuit the raster lines of the television picture would be visible in a distracting manner in the photograph, photographic slide or cine-film recording. Multiple interlace has been proposed to correct this. The said Patent proposes, starting from a single interlaced picture such as produced in accordance with television standards, to shift for each picture or frame period (which includes two field periods) the vertical scan of the raster in an incremental sequence. By way of example, a shift of 4 .mu.s during 16 frames is mentioned which for a line period equal to (approximately) 64 .mu.s results in a total shift over the distance of one line width. After 16 shifted frames, that is to say after 32 field rasters, the television picture thus formed by multiple interlace is converted to the photograph, photographic slide or cine film recording.
Practical experience has taught that such multiple interlace is only partly effective. Very slight deviations from the ideal shift pattern result in the line structure becoming visible again in the picture. These deviations may for example, be caused by: non-stable synchronization during the scan; mutual influencing of the line or horizontal deflection and the field or vertical deflection of an electron beam producing the television picture; magnetic stray fields in the case of magnetic electron beam deflection; disturbances of supply voltages and supply currents; disturbances of the anode high voltage of the picture display tube comprising the display screen; etc.